Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H77/00—Protective overload circuit-breaking switches operated by excess current and requiring separate action for resetting
  • H01H77/02—Protective overload circuit-breaking switches operated by excess current and requiring separate action for resetting in which the excess current itself provides the energy for opening the contacts, and having a separate reset mechanism
  • H01H77/10—Protective overload circuit-breaking switches operated by excess current and requiring separate action for resetting in which the excess current itself provides the energy for opening the contacts, and having a separate reset mechanism with electrodynamic opening
  • H01H77/102—Protective overload circuit-breaking switches operated by excess current and requiring separate action for resetting in which the excess current itself provides the energy for opening the contacts, and having a separate reset mechanism with electrodynamic opening characterised by special mounting of contact arm, allowing blow-off movement
  • H01H77/104—Protective overload circuit-breaking switches operated by excess current and requiring separate action for resetting in which the excess current itself provides the energy for opening the contacts, and having a separate reset mechanism with electrodynamic opening characterised by special mounting of contact arm, allowing blow-off movement with a stable blow-off position
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H1/00—Contacts
  • H01H1/12—Contacts characterised by the manner in which co-operating contacts engage
  • H01H1/14—Contacts characterised by the manner in which co-operating contacts engage by abutting
  • H01H1/20—Bridging contacts
  • H01H1/2041—Rotating bridge
  • H01H1/205—Details concerning the elastic mounting of the rotating bridge in the rotor
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H1/00—Contacts
  • H01H1/12—Contacts characterised by the manner in which co-operating contacts engage
  • H01H1/14—Contacts characterised by the manner in which co-operating contacts engage by abutting
  • H01H1/22—Contacts characterised by the manner in which co-operating contacts engage by abutting with rigid pivoted member carrying the moving contact
  • H01H1/221—Contacts characterised by the manner in which co-operating contacts engage by abutting with rigid pivoted member carrying the moving contact and a contact pressure spring acting between the pivoted member and a supporting member

Definitions

• the present invention relates to a low-voltage circuit breaker, i.e., for applications with operating voltages up to 1000 volts.
• Low-voltage industrial electrical systems characterized by high currents and power levels normally use specific devices, commonly known in the art as automatic power circuit breakers.
• circuit breakers are designed so as to provide a series of features required to ensure the correct operation of the electrical system in which they are inserted and of the loads connected to it. For example, they ensure the nominal current required for the various users, allow correct insertion and disconnection of the loads with respect to the circuit, protect the loads against abnormal events such as overloading and short-circuits by opening the circuit automatically, and allow to disconnect the protected circuit by galvanic separation or by opening suitable contacts in order to achieve full isolation of the load with respect to the electric power source.
• circuit breakers are available according to various industrial embodiments, the most common of which entrusts the opening of the contacts to complicated kinematic mechanisms that utilize the mechanical energy stored beforehand in special opening springs and are generally triggered, in case of electrical fault, by an appropriate protection device, typically a relay.
• a first solution forces the current to follow a given path, so that when a short circuit occurs, electrodynamic repulsion forces occur between the contacts. These repulsion forces generate a useful thrust that helps to increase the separation speed of the moving contacts with respect to the fixed contacts; in this manner, the intervention time is reduced and the presumed short-circuit current is prevented from reaching its maximum value.
• the second solution doubles the fixed contacts and the moving contacts. In this case, the flow of current is interrupted in each pole of the circuit breaker in two separate regions that are arranged electrically in series to each other, so that each region is subjected to a lower mechanical and thermal stress.
• a particularly critical aspect of known types of circuit breaker is the fact that the presence of electrodynamic repulsion forces, while contributing positively to the generation of the thrust useful for contact separation on the one hand, on the other hand helps the moving contact structure to reach the end of its stroke at high speed and therefore with great energy. This generally tends to cause violent impacts against the case of the circuit breaker, with the possibility of damaging it, and can therefore require the use of additional cushioning elements; moreover, bouncing of the moving contacts toward the fixed contacts and undesirable restrikes of the electric arc can occur.
• the likelihood of bouncing and restriking of the electric arc can be increased by the presence of additional springs, which are usually associated with the structure of each moving contact in order to facilitate an even distribution of the mechanical pressure on the two surfaces for coupling between each moving contact and the corresponding fixed contacts.
• the aim of the present invention is to provide a low-voltage circuit breaker that allows to obviate the drawbacks noted above and in particular in which opening in the short- circuit condition occurs in a manner that is optimized and functionally more effective than in known solutions, at the same time eliminating or at least minimizing the impacts that the moving contact can have against the case of the circuit breaker and the consequent negative effects caused by said impacts.
• a low-voltage circuit breaker comprising: - at least one first fixed contact, which is electrically connected to a terminal for connection to an electric circuit; a rotating moving contact, which comprises a central body from which at least one first arm protrudes, an active surface being provided at the end of said first arm, said active surface being associable/separable with respect to said fixed contact by means of a rotation of said moving contact; a rotating contact supporting shaft, which is functionally connected to an actuation mechanism of the circuit breaker and is provided with a seat that accommodates the central body of the moving contact so that the first arm protrudes externally from said seat, at least one first spring being furthermore arranged in said contact supporting shaft, said first spring being functionally coupled to the moving contact and being suitable to ensure, when the circuit breaker is closed, an adequate contact pressure between the active surface and the first fixed contact; characterized in that at least one first abutment surface is provided on said central body of the moving contact and is suitable to
• FIG. 1 is a plan view of a first embodiment of the assembly constituted by the contact supporting shaft, the moving contact with a single arm, and a fixed contact, which can be used in the circuit breaker according to the invention;
• FIG. 2 is a plan view of a second embodiment of the assembly constituted by the contact supporting shaft, the moving contact with a single arm, and a fixed contact, which can be used in the circuit breaker according to the invention;
• FIG. 3 is a plan view of a third embodiment of the assembly constituted by the contact supporting shaft, the moving contact with a single arm, and a fixed contact, which can be used in the circuit breaker according to the invention;
• FIG. 4 is a plan view of the moving contact of Figure 1 during abutment against the contact supporting shaft, during the separation of the active surface from the respective fixed contact following a short circuit;
• - Figure 5 is a partial perspective view of a contact supporting shaft coupled to a moving contact and to a mechanism for the actuation of the circuit breaker;
• FIG. 6 is a plan view of a possible embodiment of the assembly constituted by the moving contact and the contact supporting shaft, for a circuit breaker with double contacts.
• a pole of the low- voltage circuit breaker generally comprises at least one first fixed contact 1, which is connected electrically, by means of an appropriately configured conductor 2, to a terminal for connection to an electric circuit, according to embodiments that are widely known in the art and are therefore not described in detail; the pole furthermore comprises a rotating moving contact 10 and a rotating contact supporting shaft 20, which is shown in cross-section in Figures 1 to 4 for the sake of greater clarity of illustration and is functionally connected to the moving contact 10 and to a circuit breaker actuation mechanism 30.
• said actuation mechanism 30 generally comprises a kinematic system with opening springs 31 and allows to connect functionally the contact supporting shaft 20 to a lever for the manual actuation of the circuit breaker 32.
• the circuit breaker moreover, is usually provided with a protection device (not shown) for protection against electrical faults, typically a relay, which trips when an electrical fault occurs, causing the actuation of the actuation mechanism 30, with consequent rotation of the contact supporting shaft 20 and release of the circuit breaker.
• a protection device typically a relay, which trips when an electrical fault occurs, causing the actuation of the actuation mechanism 30, with consequent rotation of the contact supporting shaft 20 and release of the circuit breaker.
• the operation of the protection relay and of the actuation mechanism 30, as well as the corresponding methods for their functional connection to each other and to the other parts of the circuit breaker, are also widely known in the art and therefore are not described further.
• the rotating contact supporting shaft 20 has a seat 21 that is contoured appropriately so as to have at least one interaction surface 22, and a pivot 23 is fixed in the seat 21.
• the rotating moving contact 10 has a contoured central body 11, from which at least one first arm 12 protrudes; an active surface 13, for example a contact plate or pad, is arranged at the end of said arm and can be coupled/separated electrically with respect to the fixed contact 1 following the rotation of said moving contact 10.
• the moving contact 10 is functionally connected to the shaft 20 and is arranged so that the central part 11 is accommodated in the seat 21, so that the end of the arm 12 protrudes transversely outside it; preferably, the moving contact 10 is connected to the shaft 20 by coupling a hole 14 formed in the central body 11 to the pivot 23, according to a solution that is advantageous from the point of view of manufacture and assembly.
• the functional connection between the shaft 20 and the moving contact 10 might be provided in different manners, for example by providing the pivot on the body of the moving contact and the coupling hole in the shaft, or by providing a floating coupling exclusively by means of one or more springs arranged in the seat 21 and suitably connected to the shaft and to said moving contact, or in other manners, provided that they are compatible with the application.
• first abutment surface 15 on the contoured central body 11 of the moving contact 10 there is at least one first abutment surface 15, which is suitable to interact functionally against the complementarily shaped surface 22 for the purposes that will become better apparent in detail hereinafter.
• At least one first cam-like surface 16 is furthermore provided on the central body 11 of the moving contact 10 and is contiguous to the abutment surface 15 and arranged between said abutment surface and the extension of the arm 12; furthermore, at least engagement means 24 and an additional pivot 25 are arranged on the shaft 20 on mutually opposite sides with respect to the body of the moving contact 10.
• the engagement means 24 preferably comprise a second pivot 24, which is rigidly fixed to the shaft 20, while the third pivot 25 is functionally coupled to the moving contact 10 so that it can move with respect to it and is arranged so that its ends are inserted in slots 26 formed in the contact supporting shaft 20.
• additional engagement means which preferably comprise a fourth pivot 27 which, taking as reference the first pivot 23, is fixed to the shaft 20 in a substantially symmetrical position with respect to the second pivot 24; in turn, the third pivot 25 is functionally coupled to the moving contact 10 so that it can move with respect to it and is connected to the fourth pivot 27 by virtue of two linkages 28
• At least one spring is generally associated with the moving contact 10 and is suitable to ensure, when the circuit breaker is closed, an adequate contact pressure between the active surface 13 and the corresponding fixed contact 1.
• the circuit breaker according to the invention preferably uses at least two traction springs 8 (only one of which is visible in
• circuit breaker The operation of the circuit breaker according to the invention is now described with reference, by way of example, to the embodiment shown in Figures 1 and 4.
• the energy transmitted by the moving contact 10 to the shaft 20 is therefore not only removed from the possible impact against the case of the circuit breaker but is actually used to overcome the inertia of said shaft and trigger its rotation prior to the tripping of the protection relay, which in any case acts immediately after the above described effect and causes the release of the actuation mechanism 30 in a fully conventional manner. Therefore, this allows, with respect to known solutions, to perform more rapid opening actions and to reduce the mechanical and electrical stresses that the active parts must withstand in short-circuit conditions, with the beneficial consequence that the behavior of the circuit breaker over its useful life is improved significantly and its useful life is itself extended.
• the innovative result of the transmission of energy from the moving contact to the rotating shaft requires only the contour of the moving contact to be provided with the abutment surface required to interact with the corresponding surface formed on the shaft and is substantially independent of the type of functional coupling between the shaft and the moving contact and of the contour of the remaining part of said moving contact; for example, in addition to the solutions described above, it would be possible to use a moving contact that is contoured without cam-like surfaces, as shown schematically in Figure 3, or to connect the moving contact to the shaft by using one or more coupling springs conveniently arranged in the seat without using pivots, or in any other manner so long as it is compatible with the application.
• the circuit breaker is provided with a first fixed contact 1 and with a second fixed contact 3, which are connected electrically, by virtue of appropriately configured conductors 2, to corresponding terminals for connection to an electric circuit.
• the rotating moving contact 10 has a contoured central body 11 from which two arms 12 protrude; two active surfaces 13 are arranged at the ends of said arms and in mutually opposite directions with respect to the rotation axis and can be coupled/separated with respect to the corresponding fixed contacts 1 and 3 as a consequence of the rotation of said moving contact 10.
• first and second abutment surfaces 15 on mutually opposite sides and substantially symmetrically with respect to the rotation axis and therefore with respect to the hole 14; correspondingly, the seat 21 of the shaft 20 is contoured so as to form two interaction surfaces 22, against each of which an abutment surface 15 acts in a manner that is functionally entirely similar to what has been described for a moving contact with a single arm.
• the functional connection between the shaft and the moving contact according to various constructive configurations and to adopt or not also the contour with the cam-like surfaces.
• the fixed pivots 24 or 27 or 34 can be replaced in a fully equivalent manner by other engagement means that allow the engagement of the ends of the springs 8 in a manner that is functionally similar to the action of a single fixed pivot: for example, it is possible to use two pivots that are structurally independent of each other and are fixed to the shaft, or two coupling elements coupled to the shaft, or two seats formed therein and suitable to allow the anchoring of the ends of the springs 8, or other means, so long as they are compatible with the application.
• circuit breaker according to the invention fully achieves the intended aim, providing a significant series of advantages with respect to the known art and being usable both as a standard circuit breaker and as a current limiter.
• circuit breaker thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may furthermore be replaced with other technically equivalent elements.
• materials employed, as well as the dimensions, may be any according to the requirements and the state of the art.

Landscapes

• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Breakers (AREA)
• Control Of Eletrric Generators (AREA)
• Control Of Motors That Do Not Use Commutators (AREA)
• Oscillators With Electromechanical Resonators (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

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ID=11448576

Family Applications (1)

Country Status (7)

Cited By (2)

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Citations (4)

Family Cites Families (5)

• 2001
  • 2001-11-06 IT IT2001MI002327A patent/ITMI20012327A1/it unknown
• 2002
  • 2002-10-30 RU RU2004126853/09A patent/RU2295169C2/ru active
  • 2002-10-30 ES ES02787529.3T patent/ES2537297T3/es not_active Expired - Lifetime
  • 2002-10-30 WO PCT/EP2002/012167 patent/WO2003041106A1/en not_active Application Discontinuation
  • 2002-10-30 US US10/494,303 patent/US6924445B2/en not_active Expired - Lifetime
  • 2002-10-30 CN CNB028238885A patent/CN1290137C/zh not_active Expired - Lifetime
  • 2002-10-30 EP EP02787529.3A patent/EP1442467B1/en not_active Expired - Lifetime

Patent Citations (4)

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